Cnu 17 Sustainable Transit Networks Lieberman

What we’ll cover

• Types of transit networks and their attributes

• Transit networks and placemaking• Interaction between roadway

networks and transit networks

What’s a transit network?

Transit Network: the spatial configurationof the individual lines of a transit system

What’s a sustainable transit network?

1. Enabling: people can travel without depending on private vehicles

2. Efficient: consumes least amount of resources for what you get

3. Fast: allows for timely travel4. Affordable: can be maintained in all

economic climates

Transit Network Typologies

Radial Grid Hub and SpokeAmorphous

Amorphous Networks

Amorphous Networks

• Confusing• Difficult to coordinate transfers• Not a network that you’d ordinarily

design• May be all that can be done on

older street patterns

Radial Networks

Radial Networks

• Ideal for serving one central activity center

• Inflexible to changes in activity locations• Access any point on network with a

single transfer • Can require out-of-direction travel• Poor continuity on grid street systems

Grid Networks

Spacing: 0.5 mile or less

Grid Networks

¼ mile walk

Frequency: 12 minutes or less

Grid Networks

Grid Networks

• Ideal for area wide coverage• Needs high density to justify frequent

service• Best suited to grid street networks• Greater likelihood of transfers• Not convenient in low-density areas

Hub and Spoke Networks

5%5%

CBD

95%95%

Hub and Spoke Networks

• Ideal for serving many activity centers• Less frequent service can still be

attractive• Relatively economical to operate• Timed transfers are essential• Transfer facilities should be of high

quality

Enabling

Efficient

Fast

Affordable

to center

elsewhere


local bus

rapid transit

commuter rail

Transit Networks and Placemaking


Radial Grid Hub and SpokeAmorphous

bus line

rail line


CBD


TOD?

4 localities accessed directly

CBD


TOD?

7 localities accessed directly

CBD

Roadway vs. Transit Networks

Most forms of transit – but not all –are dependent on the roadway network


Surface transit needs roadways to access potential riders


Potential riders need streets and sidewalks to access transit


Connectivity and Density of the roadway network are critical to transit

Network Connectivity

Network Density

1/4 mile1/4 mile

Network Density

Network Density

1/2 mile1/2 mile

Conclusions

• Networks are unseen; understand the big picture before tinkering with the details

• Sustainable transit networks must be enabling, efficient, fast, and affordable

• To serve one principle activity node: - Radial transit network is best

• To serve many dispersed activity nodes:

Conclusions

• To serve one principle activity node: - Radial transit network is best

• To serve many dispersed activity nodes:– Grid: frequent transit service in dense

areas with grid street system– Hub-and-Spoke: for most other

situations

Conclusions

• Connectivity: connected streets permit transit to reach riders and riders to reach transit

• Density: streets suitable for transit service should be spaced every half mile to ensure an easy walk to transit

Conclusions

• Intense activities should be located near a transit network’s points of confluence

Conclusions

Cnu 17 Sustainable Transit Networks Lieberman

Business

Transcript of Cnu 17 Sustainable Transit Networks Lieberman